Echo-ranging devices



June 12, 1956 R. A. FRYKLUND ECHO-RANGING DEVICES 2 Sheets-Shea: 1

Filed April 15, 1953 IN VENTOI? ROBE/2T A. FRVKLUND 13v &

A 0 NEY June 1956 R. A. FRYKLUND 2, 74

ECHO-RANGING DEVICES Filed April 15, 1953 2 Sheets-Sheet 2 RECEIVER AMPLIFIER DE ECTOR 6 DRIVE/2 g E 64- 6/ WAISDUCER /-w.=-To/2 ROBERTA. FRYKLUND BY (ZZ fi AT 0/? EV cho-ems DEVICES Robert A. Frylrlund, Dedham, Mass., assignor to Raytheon Mannfacturing-.Conlpany, Newton, 'Mass a cor-- swaths o {De awa e Application April 15, 1953, Serial No. 348,865 filain s- 34 3) This invention relates to pulse echo distance-measuring devices and moreparticularly to a keying system found to be desirable in some depth sounding equipment.

.In sonic depth sounding equipment, whichis to-be used for inland waterways primarily for navigational purposes, the range required is relatively short, for example, on the order of eighty feet, but it is desirable that the soundings be obta' red as rapidly as possible. Accordingly, the sonic tr nsmitter is keyed as often as is possible for the desired maximum range. For example, when the desired maximum range is on the order of eighty feet, the system would be keyed on the order of 1800 times per minute. In previous systems whereinmeehanical contacts were used to key the system, wear of the contacts caused a change in the zero triggering position, and, hence, introduced an error into thy? pth indications displayed by the device. v V

This invention diselose s a keying system wherein the mov able lceying elements are the plates of a condenser and do not contact each other. Hence, there is no wear and,.hence, substantially no change in the zero setting This invention further discloses a particular electronic circuit-useful for transforming the .ohtput wave shape of .the condenser to a useful keying pulse. Briefly, thisis accomplished by connecting the movable plate of the condenser to ground, connecting the stationary plate .of the condenser to a voltage source through an impedance .andconplingthe stationary plate to the grid of a thyra tron whose voutput :is used to synchronize the quench rate of a self-quenching ,oscillator whose output is used to drive the transducer.

This invention further discloses a particular housing arrangement for the electronic components of the system comprising .a case having .a hinged cover to which is attached the indicator scale. Hinged .to the cover .is a support plate carrying ,the mechanical components of the keying .and indicating system such that all components of the system are readily accessible by opening the hinged .cover and swinging open the plate support.

Other and :further objects and advantages .of this in- Mention will become apparent as the description thereof progresses, reference being had to the accompanying rawi 1 r n= Fig. l illustrates,apartiallybrokenaway front elevation ,viewof the indicator components of asystem embodying this invention;

-Fig. 2 illustrates a partial crossrsectional topplan view vof.thedeviceshown in Big. 1

Fig. 3 is apar tiallybrolgen away perspective view illustrating details of the hinged ,snpport structure .utilizedrby the device illustrated in Figs, land 2; and

Fig. 4 is a schematic diagram of a system embodying this invention.

keferring now t o figs} through 3, theret-is shown a cas .s acta -li sq tai t t fih itqqt lat element a keyer and indicator system of an echo-ranging device. Case is substantially oblong in shape and may be made, for example, in the form of a metal stamping or P. .by an nsulatingsnpport member 26.

2,750,574 Patented June 12,

casting. Case 10 has a cover 11 attached to case 10 by a hinge 12. The front of cover 11 contains a circular portion of glass 13. Glass 13 contains around the periphery thereof scale numbers 14 indicative of the depth of the water body being measured by the depth sounder system utilizing this particular keyer and indicator systern. Positioned inside the ring of numbers is an annular transparent section 15, the remainder of the glass being rendered substantially opaque by a material, such as par 6- Positioned behind the cover '11 is a support plate 1-7, which is hinged to coverll by means of a hinge 18. Plate 17 may be fastened lIfbOSltlOll withrespect to cover 11 such that it is parallel to theglass portion 13 in cover 11 ,by means of thumb screws, not shown. Attached to plate 17 is a motor 19. Motor 19is positioned behind plate 17 and has the shaft 20 thereofextending outwardly through an apertnre in the plate 17. Rigidly attached to shaft 29 is an arm 21 which, as shown here, is pivoted substantially transversely about its mid-point on shaft 20. Fastened to one end of arm 21 is a neon indioator lamp 22, which is in registry with the annular transparent section of the glass 13. The lamp 22 is covered ,with opaque material, as at 23, for all portions visible through glass ring 15 except a thin radially extending slit thereof appearing behind the transparent por on 5- w i i Attached to the other end of arm 21 is a plurality of conductive plates 23 which serv as the movable nae): 91 s ndq se Bees 3 a PQ d'P f to the snpport member 17 and are spaced by means of spacers 255; Since the plates 23 and spacers 24, asiwell as the 21 and shaft 28, are conductive, the plate's 'l 3 .are effectively grounded through the motor 19. Plates are adapted'to pass between a pluralityof stationary s 25 "nsulatedlysupported at the botton rof plate '17 member 26 is attached to plate v17 by means throogh slotted holes in member 26 denser plates pass between the plates 25. Lin general, .thisadjustrnent ,will be made such that the keyingpulse produced by thecondensenusing plates 23 and 25, occurs Isubstantially at thetirne the neon'lamp 22 passes the zero marlc at .the topof the scale. It maybe noted that, since the condenser plates 23 are at the opposite end of the .rod 21 from the lamp 22, a balanced structure maybe Tobtained, which may be rotated at highspeeds without any substantial vibrations.

Inorderto supply an indicating signal to the lamp 22, vthe router end thereoflwhich constitutes one terminal of the lamp, is connected through a metallic clamp 27 to the .arrnllland, hence, toground through the motor .19. The other endrof the lamp 22 is attached to a metallic clamp 28 insulatedly mounted on arm -21Qand connected to .a .slipring insulatedly mounted on shaft 20,behind ,arm 21. An enna brush 30 engages slip ring29 and'is insulatedly rnounted as at 31 on support plate 17. Ahplication of the desired signal to the brush 39 connects the signal across {the lamp 21, thereby producing illumination thereof. if i i Referring now to ,Fig. 4, there .is shown a diagram, of a system utilising ,the keyer and indicator structure illustrated in ,Figs. 1 through 3 The movable plate 2 3 of theicondenser 32 is connected .to ground through the arm 21. The stationary plate 25 of the condenser 32is con- 37 is connected to I through a oue nchin g resistor 38 and to ground through a charged dumping condenser 39. The screen grid 40 of thyratron 36 is connected to the grid 35 through a current-limiting resistor 41, and the grid 35 is, in turn, connected to ground through a grid-load resistor 42. The cathode 43 of thyratron 46 is connected to ground through a cathode load resistor 44, and to B+ through bleeder bias resistors 45 and 46 in series. Cathode 43 is also connected through a condenser 47 in parallel with a resistor 48 in series with a resistor 49 to the grid 50 of the self-quenching oscillator tube 51. The cathode 52 of tube 51 is connected to a tap on an inductor 53, one end of which is grounded and the other end of which is connected through a condenser 54 to grid i). Inductor 53 is resonated at the desired oscillation frequency of the tube 51 by a condenser 55 in parallel with inductor 53. The screen grid 56 of tube 51 is connected to B+. The suppressor 57 of tube 51 is connected to the cathode 52 and the plate 58 thereof is connected through the primary winding 59 of the transformer 60 and a resistor 61 in series to B+.

The secondary Winding 62 of transformer 60 feeds a driver 63, which may be, for example, a pair of power amplifier tubes fed in push-pull. The output of the driver 63 is fed to a transducer 64, which may be, for example,

of the magnetostrictive or crystal type and preferably is made substantially resonant at the oscillation frequency of the tube 51. The transducer 64 projects sound waves downwardly toward the bottom 65 of the water body, whose depth is to be measured, and the returning echo signals are picked up by the transducer and fed through a receiver amplifier detector 66 to the brush 30 feeding the neon lamp 22.

In operation, the meshing of the plates 23 of the condenser 32 with the plate 25 causes the capacity thereof to increase. As a result, the condenser 32 charges through the resistor 33, causing a negative voltage to be applied to the grid 35 of tube 36 as the condenser 33 is increasing in capacity. However, as soon as the plates have become completely engaged and start to disengage, the capacity of condenser 32 decreases, causing a positive voltage to be applied to the grid 35 of the thyratron 36 through the condenser 34, thereby firing the thyratron. The thyratron 36 is subsequently extinguished due to the fact that the condenser 39 in the plate circuit thereof discharges rapidly to a potential below the sustaining potential of the thyratron, and the resistor 38 is sufficiently large to prevent a discharge sustaining current to be drawn therethrough. By suitable adjustment of the size of the condenser 39 and resistor 38, the duration of the firing to thyratron 36 may be made on the order of a millisecond or less. Firing of the thyratron 36 causes a positive pulse to be applied to the grid 5t) of the oscillator tube 51, thereby causing the oscillator tube 51 to burst into oscillations. These oscillations rapidly build up in amplitude until grid current is drawn, charging condenser 54 to a point Where the grid 50 is biased sufliciently far below cutotf of the tube 51 to extinguish the oscillator. The condenser 54 discharges through the resistors 48 and 49 and the resistor 44 to a point Where oscillations may again occur by the tube 51. The size of the resistor .8 and condenser 54 are adjusted such that the free-running quench rate, that is, the rate at which bursts of oscillation would be produced by the oscillator 51, is somewhat less than the repetition rate of the pulse Output of the thyratron 36. As a result, the bursts of oscillation produced by the oscillator 51 are synchronized with the triggering of thyratron 36, and, therefore, the burst of oscillations may be fed to the transducer 64 substantially at the time the indicator lamp 22 passes the zero position on the scale. The regenerative feedback of the oscillator 51 is sufficiently great to allow the oscillator to block after a few hundred cycles or less of oscillations have occurred, such that if the oscillator is operating in a supersonic range, as is usually the case, the length of the burst of oscillations is on the order of a few milliseconds. This initial burst of oscillations appears on the lamp 22 and gives an indication which may be used for zero adjustment of the position of the stationary plates 25 of the condenser 32.

This completes the description of the particular embodiment of the invention illustrated herein. However, many modifications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example, other types of oscillator driver circuits could be used and other types of indicators besides the lamp 32, such as permanent record indicators wherein marks are made on the sensitive paper indicative of echo signals, could be used with the condenser keying arrangement illustrated herein. Accordingly, it is desired that this invention be not limited by the particular details of the species illustrated herein except as defined in the appended claims.

What is claimed is:

l. A pulse echo system comprising a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, and an indicator for said pulse echo system having a movable element mechanically ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

2. A pulse echo system comprising a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, and a visual indicator for said pulse echo system having a movable element mechanically ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

3. An echo-ranging system comprising a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, and an indicator for said pulse echo system having a movable element mechanically ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

4. An echo-ranging system comprising a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, and a visual indicator for said pulse echo system having a movable element mechanically ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

5. A pulse echo system comprsing a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, a stationary plate of said condenser being coupled to a voltage source through a charging impedance and coupled to the control grid of a grid-controlled gaseous discharge device, a movable plate of said condenser being grounded, and an indicator for said pulse echo system ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

6. A pulse echo system comprising a source of energy to be transmitted, a keying system for said source comprising a mechanically variable condenser, a stationary plate of said condenser being coupled to a voltage source through a charging impedance and coupled to the control grid of a grid-controlled gaseous discharge device, a movable plate of said condenser being grounded and being attached to apparatus for periodically moving said movable plate past said stationary plate, and an indicator for said pulse echo system ganged to said condenser, which indicator is adapted to indicate the presence of reflected energy caused by said transmitted energy.

Granqvist Mar. 20, 1945 Hurley Aug. 8, 1950 

